010 



EMBRYONIC DEVELOPMENT OF PURPURA. 



at A, Fig. 325 : and the embryoes are often, in the first instance, 

 so completely buried within this, as only to be discoverable by 

 tearing its portions asunder ; but some of them may commonly be 

 found upon its exterior ; and those contained in one capsule very 



Fig. 325. 



Later stages of Embryonic Development of Purpura la'pillus: — 

 A, conglomerate mass of vitelline segments, to which were attached 

 the embryoes, <%, b, c, d, e : — b, full-sized embryo, in more ad- 

 vanced stage of development. 



commonly exhibit the different stages of development represented 

 in Fig. 324, H — k. After a short time, however, it becomes ap- 

 parent that the most advanced Embryoes are beginning to swallow 

 the Yolk-segments of the conglomerate mass ; and capsules will 

 not unfrequently be met-with, in which Embryoes of various sizes, 

 as a, b, c, d, e (Fig. 325, a), are projecting from its surface, their 

 difference of size not being accompanied by advance in develop- 

 ment, but merely depending upon the amount of this ' supple- 

 mental ' Yolk which the Embryoes have respectively gulped-down. 

 For during the time in which they are engaged in appropriating 

 this additional supply of nutriment, although they increase in 

 size, yet they scarcely exhibit any other change ; so that the large 

 Embryo, Fig. 325, e, is not apparently more advanced as regards 

 the formation of its organs, than the small embryo, Fig. 324, K. 

 So soon as this operation has been completed, however, and the 

 Embryo has attained its full bulk, the evolution of its organs 



